1. Field of the Invention
The present invention relates to an image processing system for recording or reproducing image information.
2. Description of the Prior Art
Conventionally, such a kind of image processing system has been constituted as shown in FIG. 1. Practically speaking, in a conventional system shown in FIG. 1 reference numeral 1 denotes an image information input apparatus for inputting image information, i.e., what is called a reader; 2 is a line buffer memory for storing the image information inputted from the reader 1 for tens of horizontal synchronization periods, namely, for tens of lines; 3 is an optical recording/reproducing apparatus such as a photo disc or the like for optically recording or reproducing the image information; 4 is a line buffer memory similar to the memory 2; and 5 is an image information output apparatus for visually outputting the image information by printing it, i.e., a printer.
The conventional system shown in FIG. 1 operates at the timing as the overall system using a horizontal synchronization signal HSYNC from the printer 5 as a reference signal. However, each unit of the line buffer memories 2 and 4, photo disc 3 and printer 5 operates on the basis of a reference clock of the individual system for every unit. The frequencies or phases of the reference clocks of the respective units do not always completely coincide with one another. In addition, the horizontal sync signal HSYNC from the printer 5 is formed in association with the rotation of a mechanical rotating mechanism, e.g., polygon scanner in the printer 5, so that there is the drawback of a slight time-dependent fluctuation, i.e., what is called a "jitter".
Generally, when image information is recorded on a recording medium, the signal to be recorded has to be successive in the case of continuously recording, instead of a sector method of recording. However, as mentioned above, if each unit operates in response to the clock of the individual systems and also jitter is included in the horizontal sync signal HSYNC which is used as a reference signal for the overall operation timing, the image starting positions of respective lines do not coinide, so that discontinuity occurs in the recording images in the boundary portion of the respective lines. Further, in the case where the readout of the image information from the line buffer memory 2 is controlled on the basis of the reference clock for driving the photo disc 3 in order to avoid the occurrence of such discontinuity, a deviation of the horizontal synchronization will have occurred little by little in the recording images for every page due to the frequency deviation between the reference clock for driving of the printer 5 and the reference clock for driving of the photo disc 3.
To prevent such a deviation in the images, as shown in FIG. 2, it is necessary to use page buffer memories 6 and 7, each having a large capacity in place of the line buffer memories 2 and 4, and to control the readout to the print-out of the image information on a page unit basis. Therefore, there is a drawback such that a complicated and expensive memory device has to be used.